Cell signaling and Cell cycle - Vocabulary Flashcards

Vocabulary flashcards covering key terms from the lecture notes on cell signaling and the cell cycle.

Cell signaling

Process by which cells communicate through signaling molecules and receptors to coordinate growth, differentiation, and responses.

Receptor

A protein that binds a signaling molecule (ligand) and initiates a downstream cellular response.

Signaling molecule (ligand)

A molecule that binds to a receptor to trigger a signal transduction pathway.

Second messenger

Intracellular molecules that relay and amplify signals from receptors to target proteins (e.g., DAG, IP3, Ca2+).

PIP2

Phosphatidylinositol 4,5-bisphosphate; a membrane lipid cleaved by PLC into DAG and IP3.

DAG

Diacylglycerol; stays at the membrane and activates signaling molecules such as protein kinase C.

IP3

Inositol trisphosphate; diffuses in the cytosol to release Ca2+ from internal stores like the endoplasmic reticulum.

Ca2+ (calcium ion)

A key intracellular second messenger that activates various signaling proteins.

Endoplasmic reticulum

Organelle that stores Ca2+ and releases it into the cytoplasm in response to IP3.

Signaling pathway

A cascade of molecular interactions triggered by receptor activation, leading to a cellular response.

Mitogen

A chemical messenger that stimulates a cell to enter the cell cycle and divide.

Cyclin-dependent kinase (CDK)

A kinase that drives cell cycle progression when bound to a cyclin; activity is regulated by cyclins.

Cyclin

Regulatory proteins whose levels rise and fall during the cell cycle to activate CDKs.

Cyclin D/CDK4/6

CDK-cyclin complex that promotes G1 progression and helps push the cell toward S phase.

Cyclin E/CDK2

CDK-cyclin complex that drives the G1/S transition and entry into S phase.

Cyclin A/CDK2

CDK-cyclin complex that promotes S phase progression and S-to-G2 transitions.

Cyclin B/CDK1

CDK-cyclin complex that drives the G2/M transition and entry into mitosis.

G1 phase

First gap phase; cell growth and preparation for DNA replication.

S phase

DNA synthesis phase where the genome is replicated.

G2 phase

Second gap phase; cell growth and preparation for mitosis; centrosomes duplicated.

Mitosis

Nuclear division that partitions duplicated chromosomes into two daughter cells (followed by cytokinesis).

Prophase

Chromosomes condense; the mitotic spindle forms and the nuclear envelope begins to break down.

Metaphase

Chromosomes align at the metaphase plate; spindle fibers attach to kinetochores.

Anaphase

Sister chromatids separate and are pulled to opposite poles.

Telophase

Nuclei reform around separated chromosomes; chromosomes de-condense.

Interphase

Phase including G1, S, and G2 when the cell grows and prepares for division (not actively dividing yet).

G1 checkpoint

Quality control before S phase; checks condition of the cell and DNA integrity.

G2 checkpoint

Quality control before mitosis; ensures DNA replication completed and intact.

M checkpoint

Spindle assembly checkpoint; ensures all chromosomes are properly attached before anaphase.

Apoptosis

Programmed cell death; a controlled process to remove damaged or unnecessary cells.

Binary fission

Asexual cell division in prokaryotes; the chromosome is replicated and the cell splits.

Prokaryotic cell cycle

A simplified cycle (DNA replication and binary fission) without a true nucleus.

Centrosome

Organelle that organizes the mitotic spindle and duplicates during interphase.

DNA replication

Process of copying the genome during S phase so two sister chromatids are formed.